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| author | Andreas Kling <kling@serenityos.org> | 2021-08-22 12:57:58 +0200 |
|---|---|---|
| committer | Andreas Kling <kling@serenityos.org> | 2021-08-23 00:02:09 +0200 |
| commit | a930877f31fb117ce4b38d4782dd288093700d8a (patch) | |
| tree | be22fc9f535db876433c71587e0e34602ebd378e /Kernel/Memory/MemoryManager.cpp | |
| parent | 1b9916439fc93395386d160e25858b300444c4db (diff) | |
| download | serenity-a930877f31fb117ce4b38d4782dd288093700d8a.zip | |
Kernel: Mape quickmap functions VERIFY that MM lock is held
The quickmap_page() and unquickmap_page() functions are used to map a
single physical page at a kernel virtual address for temporary access.
These use the per-CPU quickmap buffer in the page tables, and access to
this is guarded by the MM lock. To prevent bugs, quickmap_page() should
not *take* the MM lock, but rather verify that it is already held!
This exposed two situations where we were using quickmap without holding
the MM lock during page fault handling. This patch is forced to fix
these issues (which is great!) :^)
Diffstat (limited to 'Kernel/Memory/MemoryManager.cpp')
| -rw-r--r-- | Kernel/Memory/MemoryManager.cpp | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/Kernel/Memory/MemoryManager.cpp b/Kernel/Memory/MemoryManager.cpp index 237e60e6d7..324f9cb083 100644 --- a/Kernel/Memory/MemoryManager.cpp +++ b/Kernel/Memory/MemoryManager.cpp @@ -1004,9 +1004,9 @@ PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr) u8* MemoryManager::quickmap_page(PhysicalAddress const& physical_address) { VERIFY_INTERRUPTS_DISABLED(); + VERIFY(s_mm_lock.own_lock()); auto& mm_data = get_data(); mm_data.m_quickmap_prev_flags = mm_data.m_quickmap_in_use.lock(); - SpinlockLocker lock(s_mm_lock); VirtualAddress vaddr(KERNEL_QUICKMAP_PER_CPU_BASE + Processor::current_id() * PAGE_SIZE); u32 pte_idx = (vaddr.get() - KERNEL_PT1024_BASE) / PAGE_SIZE; @@ -1025,7 +1025,7 @@ u8* MemoryManager::quickmap_page(PhysicalAddress const& physical_address) void MemoryManager::unquickmap_page() { VERIFY_INTERRUPTS_DISABLED(); - SpinlockLocker lock(s_mm_lock); + VERIFY(s_mm_lock.own_lock()); auto& mm_data = get_data(); VERIFY(mm_data.m_quickmap_in_use.is_locked()); VirtualAddress vaddr(KERNEL_QUICKMAP_PER_CPU_BASE + Processor::current_id() * PAGE_SIZE); |